And what about this one, from a Greek lost in Gaul in the 2nd half of the 3rd cent. AD, maybe my preferred Roman portrait (hence my avatar), that can hold comparison with the most famous hellenistic portraits (as this one, Perikles on a Lycian stater end of 4th cent. BC; from Triton X). Postumus was surely patronizing the AGDEB!

And what about this one, from a Greek lost in Gaul in the 2nd half of the 3rd cent. AD, maybe my preferred Roman portrait (hence my avatar), that can hold comparison against the most famous hellenistic portraits (as this one, Perikles on a Lycian stater end of 4th cent. BC; from Triton X). Postumus was surely patronizing the AGDEB!

Well, now that one is magnificent. I always thought your avatar was from a sculpture. A guess that attests to the quality of the engraving.

I have to run to catch a flight, but if I had a chance I would post some Sesterius that I think demonstrate fine engraving. I believe one commemorates the death of a wife (horsedrawn hearse), there are some Neros, etc). I am sure you, Zach et al know the coins.

If there was a series of Roman coins I would say compare with Greek coins, it would be those.

Gotta run

BR

Mark

__________________"When you are in Rome live in the Roman style; when you are elsewhere live as they live elsewhere" St. Ambrose (340-397) to St. Augustine."

Bronze Disease (BD) started to actively pop up everywhere the reddish copper oxides had been smoothed down to the surface (cheeks and neck), as a result of the humidity from the air could now react with the once hidden cuprous chlorides.
As the surface was not patinated, I decided to put the coin in a sodium bicarbonate solution, while I had not found anywhere this exact treatment to cure bronze disease. Bronze disease produces hydrochlorid acid (HCl) which attacks the copper atoms, to create CuCl, which itself forms HCl in presence of water, an auto-alimented reaction destroying the whole coin in final. As sodium bicarbonate neutralizes HCl, it seems to be a good treatment for bronze items without patina (bicarbonate having an effect on patinas).
I let the coin some days in bicarbonate diluted in tap water, where I noticed there was no effect: of course, tap water contains Cl!!
Then a final 2 weeks bath of bicarbonate/distilled water seems to have completely laid down BD, but toned the surface color from natural red copper to a pleasant green-brown tone! I'm unable to give you the chemical reaction for this 'baking soda on BD' toning

A .. natural patina, isn't it? a 14 days natural patina vs 1940 years natural patina
The surface before/after remained basically the same (the 2nd picture may render the surface softer than it is, maybe the lighting conditions are different), save some tiny porosity where the BD had emerged.

Did any of you have ever had experimented sodium bicarbonate to treat BD? I had only heard of sodium sesquicarbonate in the bibliography, and never baking soda directly: am I missing something?

Jeff, I used a saturated solution: a teaspoon of baking soda inside a regular jam pot less than half filled.

For the patinated coins, I'm thinking now of trying to deposit a tiny quantity of humidified baking soda directly on the ill area and repeat the process as many times as necessary; this will avoid submitting the rest of the surfaces, which may be nicely patinated, to baking soda, a light base (pH > 7) with the inherent risks of reactions and alterations.

Hello everyone. I am new to the board and am enjoying looking through the old posts and learning! I was wondering what the exact amount of DW you added to the teaspoon of baking soda. In the US the jam jars are kind of small. I look forward to your response .
Glenn

I have to agree with Mark, wherever he is now---For me there is something unsurpassed in the beauty created by the Greek artisans and those influenced by them. In fact, the other day I was just thinking of what for me are some of the more captivating issues. The positive/ negative grain ear designs of Lucania, Magna Graecia; the bold, high relief of Athens-enamored Philetairos/Attalos of Lydia; Larissa; the lions of Lycian Knidos...and I'm sure I'm bypassing some of the true masterpieces. The few later Roman issues I've bumped into still seem a bit too two-dimensional and carricatured for my admittedly untrained taste. But, then again, consider where you might find me--milking the goats in the field next to Mark's

Hello everyone. I am new to the board and am enjoying looking through the old posts and learning! I was wondering what the exact amount of DW you added to the teaspoon of baking soda. In the US the jam jars are kind of small. I look forward to your response .
Glenn

To Purpleloki:
The principle is to saturate the solution, like a teaspoon of baking soda in the equivalent of a small drinking glass of DW.
Another remedy can be a stronger Base, like Ammonia, but which will remove or damage green patinas. Beware!